West Nile virus is a virus commonly found in Africa , West Asia , and the Middle East . It is closely related to St. Louis encephalitis virus found in the United States . The virus can infect humans, birds, mosquitoes, horses and some other mammals.
West Nile fever is a case of mild disease in people, characterized by flu like symptoms. West Nile fever typically lasts only a few days and does not appear to cause any long-term health effects.
More severe disease due to a person being infected with this virus can be West Nile encephalitis, West Nile meningitis, or West Nile meningoencephalitis. Encephalitis refers to an inflammation of the brain, meningitis is an inflammation of the membrane around the brain and the spinal cord, and meningoencephalitis refers to inflammation of the brain and the membrane surrounding it.